The U.S. site of the vlhc is assumed to be Fermilab.

The Steering Committee for a future very large hadron collider has been established to coordinate the U.S. effort towards a future, post-LHC, large hadron collider.

Its initial membership consists of representatives appointed by the Directors of BNL, FNAL, LBL, and Cornell University’s Laboratory of Nuclear Studies.

The Steering Committee does not manage the work of the individual institutions.

The Steering Committee will

• encourage the exchange of personnel between participating institutions
• promote coordination in planning and sharing of research facilities
• provide a mechanism for all interested parties to participate in the evaluation of the alternative technological approaches that are presently being pursued.

The Steering Committee will organize the selection of a good name and logo for the vlhc.

It will issue an annual report summarizing work of each group and setting goals for the next year.

• Working Groups are being formed.

• They are open to all and participation is welcomed from all foreign and U.S. institutions.
Magnet technologies
Accelerator technologies
Accelerator physics
   General Charge to all working groups

Explore the viability of the various parameters sets implied by the major magnet options.

First workshop will be held near Fermilab Feb 22 - 25, 1999.

"The Accelerator Physics Working Group has the responsibility for designing accelerators by interacting with the Accelerator and Magnet Technology Working Groups. The design will include both high field and low field magnet technologies. The working group will work on accelerator parameters, beam dynamics, magnet field quality, relaxation of the machine tolerance by introducing innovative and new ideas in machine design. The group will work on R&D in accelerator design to reduce the cost and increase the performance on the collider by studying a multi-dimensional accelerator parameter space."

This workshop will concentrate on many themes of Accelerator Design beside general Accelerator Design issues.

• High Field Magnet Collider lattice: Synchrotron Radiation vs. Magnetic Field. Quality at injection. Lifetime at injection.

• Low Field Magnet Collider Lattice: Aperture, Magnet Field Quality and Correction system.

• Instabilities, Ground Motion and Feedback Systems.

• Longitudinal Dynamics.

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• Magnet Technologies Working Group

Bill Foster, Fermilab
Peter Wanderer, BNL
Ron Scanlan, LBNL

Review progress in magnet R&D. Develop bases including costs for comparing different magnet designs. Monitor, encourage and coordinate progress in materials development both in academe and industry.

To coordinate the U.S. effort towards a future, post-LHC, large hadron collider, the Steering Committee for a very large hadron collide was established last spring. The Steering Committee has appointed a Magnet Technologies Working Group to deal with specialized issues related to magnets. One of the first tasks of the Magnet Technologies Working Group is to organize a workshop on magnets and related topics.

The workshop will include discussion of:

• Cost drivers for superconductor and superconducting magnets
• Manufacturing tolerances and field quality
• Cost models for cryogenic systems at various temperatures
• Beam screens and synchrotron radiation

Chris Leemann, Thomas Jefferson Lab
Waldo Mackay, BNL
John Marriner, Fermilab

Foster dialog and partnerships with industry. Develop bases including costs for comparing different designs.

Workshop being planned for February 8-12, 1999 near Thomas Jefferson Lab in Virginia.

This workshop will concentrate on rf & feeedback, diagnostics & controls, and cryogenics (and maybe at least some aspects of the vacuum system). Partial (tentative) list of topics:

General questions:

• Where are the technical uncertainties?
• What is the approximate cost of a given sub-system? Is it a "cost driver?"
• What are reasonable cost reduction strategies?
• What new technologies could be applied?

• What are the relative merits of superconducting and conventional rf?
• What is the approximate cost?
• What types of feedback are required?
• To stabilize the rf voltage (including beam loading effects)
• To stabilize the beam longitudinally
• To stabilize the transverse beam motion
• What R&D opportunities exist?

• What type of environment do we need to provide for the electronics?
• How can we minimize cable and connector costs?
• What strategies could minimize installation costs?
• What strategies could maximize reliability (and reduce maintenance costs)?
• Description of diagnostics & control desired and general specifications.
• What controls architecture would be appropriate?
• What R&D opportunities exist?

• What are the issues in comparing different operating temperatures?
• What are the relative costs for various temperatures?
• What might be the goals for cryogenic load (total heat leak)?
• What are the reliability and maintenance issues?
• What are the opportunities for R&D?

Being organized by LBNL for end of June 1999
Possible venue at Lake Tahoe or Monterey (California)
In-depth reports from each working group.
These will become the basis for the first annual report.

• collider energy

• accelerator physics issues
• superconducting material availability and cost
• magnet and R&D costs
• amount of synchrotron radiation

For a 50 TeV + 50 TeV collider

Low-field:

• Damping time too long to be helpful
• However, allows AG structure with no problems from anti-damping

• synchrotron radiation is bad; it puts power into the cryogenics.

• synchrotron radiation is good; it makes the beam emittance (size) smaller.

Low field B ~ 2 T Fermilab

Moderate field B 2 ~ 9 T

High field B 9 T ~ 12 T Fermilab

Very high field B > 12 T BNL, LBNL

Low field Probably NbTi

High, very high field
 

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BNL Magnet R&D

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LBNL Magnet R&D High Field Magnet R&D Approach

Superconductor
 

• Start building magnets with a conductor which can generate high field (~ 15 T) today: Nb₃Sn

• Start building small coils with conductors which have good promise for tomorrow:

BSSCO (HTS), Nb₃Al, "engineered" Nb₃Sn

• Use these coils as inserts in a High Field Hybrid Magnet

 
Magnet Design  

• Flexible design to explore different technologies

• Different types of conductors
• Different types of magnet construction

Wind & React vs. React & Wind

• Conductor friendly -- "racetrack" coils

Most high field conductors are brittle

• Simple and compact

• Efficient R&D magnets (faster turn around)
• Lower cost machine magnets

 
Near term goals:
 

•   A Nb₃Sn common coil magnet has been completed and will be tested shortly. Should reach 7 T (using "free" conductor left over from ITER)

 

• Next -- build another Nb₃Sn dipole, designed to reach 14 T -- complete during FY 99

 

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Fermilab High Field Magnet Program

First Nb₃Sn Short Dipole Model

Click here to start slide show

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Fermilab Low Field Magnet Program

Click here to start slide show

Low-field program goals

• 50 meter long magnet by early CY 99
• 1-2 years later full string test of a few cells (500 - 1000 meters) of a section of the 3 TeV vlhc booster

 

• NbTi is ideal for the low-field vlhc
• J_c at low field has increased by x10 since Tevatron built (MRI)
• Cost is probably < $1 /kA-meter

 

Nb₃Al is an interesting alternative.

can run at higher temperature than NbTi 

High J_c at low field Sumitomo Electric will deliver 12-meters of Nb₃Al transmission line to test this alternative.

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New and improved materials

High-temperature superconductors
 

• BSSCO and YBCO R&D is getting lots of funding from non-HEP sources.
• HEP needs to make some investment so our parameters are kept in mind.

Low-temperature superconductors

• High-field magnets 10 - 15T are likely to be built from Nb3Sn or Nb3Al.
• There has been great improvement in the performance of these conductors in the past five years, with Jc increasing almost a factor of three. The cost has also decreased somewhat.
• This improvement was driven by the ITER Project

• R&D - $1M for two years per participating company
•  ~$1M for prototype production (1 ton/vendor)
• 26 tons of production, worldwide (~$40M!), 4 tons in the US.

• The ITER Project is now dead (in the US, at least).
• HEP needs to continue the good progress for improved performance and lower cost.

A proposal to continue superconductor R&D

• Improvements can be done on a relatively small scale, $200K to $400K per year per company.
• After improvements in performance (2 to 3 years?), a major effort to reduce costs by process and economy of scale should be undertaken, $500K to $1M per year per company.
• Must offer total cost recovery and some profit during the R&D phase, because there is no market large enough to justify private investment.
• US companies have threatened to get out of the A15 business because of lack of market, so the R&D must include some foreign companies. Besides, some of the best work is done in Europe and Japan.
• This work should be driven by the needs of HEP.
 
 

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Excellence of the Fermilab site for the vlhc

 

Existence of the injector chain
Excellent Geology

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Accelerator Physics and other vlhc related R&D

 Instability issues are being addressed; solutions are being found.

 Coupled bunch transverse instability:

Marriner has designed a damper for the azimuthal mode 0 motion (coherent motion of the bunch center-of-mass). More difficult is to damp higher modes (that have smaller growth rates).

Transverse Mode Coupling Instability (TMCI)

One can raise the luminosity limit imposed by the TMCI by injecting many bunches and coalescing at high energy.

Other methods for raising TMCI threshold (recent work by Shiltsev, Danilov and Burov):
 

• RF Quadrupole
• Asymmetric vacuum chamber

 
These invite accelerator experiments.

Ground motion

Measurements (~0.01 Hz - ~100 Hz) in the dolomite layer chosen for a U.S. site at Fermilab have been made. (Shiltsev and collaborators from Novosibirsk). Effect of the measured data on alignment, closed orbit stability, and emittance preservation has been evaluated and found to be acceptable.

Tunnel cost reduction

There is progress on exploring in partnership with the private sector ways to reduce the cost of making long tunnels.

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Conclusions  

What we agree on:

• a common goal of probing the microworld to a mfermi

• a set of working parameters:

50 TeV/beam; 3 TeV injector fed from the Fermilab MI

• the vlhc must be an international project!

 

Why work on vlhc now?

Historical Perspective: typically 10-15 years elapse from first R&D magnet to last machine magnet. It is not too soon to be working on a post-LHC collider although clearly construction would not begin until the first physics results come from LHC.  

There is uncertainty in the future. We need to continue to pursue the VLHC option (at a modest level) so that we can make the most informed long-term strategy.

We are looking at

• cost reduction strategies that would allow the machine to be built with technology that is already understood.
• strategies that require new technology probably have longer time scales, and unknown cost implications.
• The use of new technologies may have societal benefits, which will be important in gaining the necessary public support.

 

What's next?

The Steering Committee will request time at the Spring HEPAP meeting in Washington to report on the results of the 3 workshops and to make a joint request for FY ’00 R&D support.